The present invention relates to a method of neutralizing allergens produced by house dust mites. More particularly, the present invention relates to a method and composition for neutralizing house dust mite feces allergens by atomizing an aqueous solution comprising a botanical extract having protease inhibitory activity such that the atomized botanical extract contacts the house dust mite feces and renders it substantially non-allergenic.
It has been known for many years that common house dust is an important cause of asthma, rhinitis and eczema in allergic individuals. Common house dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus) are prevalent in house dust. Dust mites are not insects, but are eight-legged arachnids, and are related to ticks and spiders. Adult mites are approximately 250–300 micrometers in length, and are photophobic.
House dust mites are co-inhabitants of almost every house and, because of their size and translucent body structure, cannot be seen with the naked eye. Dust mites are found in almost all home furnishing textiles and thrive in mattresses, pillows, cushions, carpets, upholstery, and soft toys etc. An adult mite can live up to about three months. The reactions caused by house dust mite feces in sensitive people can range from itchy and watery eyes, repeated sneezing and running nose, cough and bronchial asthma, to eczema. The dust on which house dust mites thrive may be cotton, wool lint, animal and human dander or hair, crumbs, pollens, and molds.
House dust mites typically feed on human skin scales. In addition to a food source, the other essential requirement for dust mite growth is adequate humidity. Dust mites are 75% water by weight and although they do not drink water, they must absorb water vapor from the air to survive. Specialized glands above their pairs of legs produce secretions high in sodium and potassium chloride, which act to absorb water vapor from surrounding air. This can only be accomplished if the surrounding humidity is sufficiently high. Relative humidities of about 65–80% at temperatures ranging from about 20 to 35° C. are optimal for dust mite growth.
A major dust mite allergen is present in dust mite fecal particles. Each dust mite produces about 20 fecal particles per day, and more than 100,000 mites may be present in a gram of dust. These fecal particles vary from about 10 to about 40 microns in size, comparable to the size of pollen grains, and become airborne during domestic activity such as making beds and vacuuming carpets. Enzymes with serine protease and/or cysteine protease activities from house dust mite feces have been shown to damage the airway epithelium. This damage increases the propensity for house dust mite allergens (including proteases) to penetrate the protective epithelium lining, interact with immune cells, and can induce the production of specific IgE molecules which can initiate an inflammatory cascade culminating in an allergic response.
Group I allergens (Dermatophagoides farinae I, and Dermatophagoides pternoyssinus I) are heat labile, 24,000 molecular weight glycoproteins, and appear to be structural homologues and have very similar N-terminal amino acid sequences. Group I allergens are regarded as the most important and are excreted in their highest concentrations by the mite's gastrointestinal tract in the form of mite's fecal particles.
Group II allergens (Dermatophagoides farinae II, and Dermatophagoides pternoyssinus II) are 15,000 molecular weight proteins with almost identical N-terminal amino acid sequences that are also secreted by the mite's gastrointestinal tract in the form of fecal allergens, although not in as high a concentration as the group I allergens. Most dust mite allergic individuals produce antibodies to both the group I and group II allergens.
The control of dust mite population in the domestic environment is one method of preventing house dust allergies. The degree of cleanliness impacts the number of house dust mites and the resulting allergen level. Common control measures include vacuum cleaning, frequent washing, and treating the carpets and bed spreads with insecticides, acaricides, and fungicides. Reducing dust mite population by interfering with the food chain has also been suggested.
Rao et al. in U.S. Pat. No. 6,060,075 disclose a composition for controlling house dust mite population. The composition comprises a plant derived acaricidal agent, which is disclosed as neem seed kernel extract, and a plant derived disinfectant agent, which is disclosed as an alcoholic extract of resins like stryax benzoin. Rao et al. disclose that a bi-weekly spray of 200 microliters/100 milligrams of culture is required for eight weeks to completely eliminate the house dust mites, and discloses that re-establishment of house dust mites after treatment with acaricides is a common problem due to the existence of nymph and eggs. Rao et al., however, fail to disclose any compositions or methods for neutralizing the feces allergen of dust mites, and simply disclose a very narrow composition for killing house dust mites, which does not necessarily neutralize the feces.
Miller in published U.S. Patent Application 2002/0022043 discloses a method for killing house dust mites in clothing and other soft materials. Miller exposes woolen or other fabrics to the vapors of certain plant oils, including wintergreen oil, lavandin oil, Ylang-Ylang oil and others. The oils are aromatherapy-grade oils produced by steam distillation. Miller generates vapors of the oils numerous ways including: placing a few drops of the oil on a paper towel, piece of cotton, or on a glass or plastic dish and then placing the treated substrate in a closed environment with the articles to be treated; spraying a mist of the oil onto the substrate to be treated, or by heating the oil to cause vaporization. Similar to Rao, Miller sets forth a method for killing house dust mites, but does not disclose methods or compositions for neutralizing house dust mite feces. Additionally, the compositions set forth by Miller are oils which can be messy to work with, can stain certain fabrics, and can be very difficult to effectively vaporize.
McKechnie et al. in UK Patent Application GB 2,363,074 disclose a method for deactivating house dust mite allergens by volatilizing an oil which comprises tea tree oil or another oil comprising terpene compounds and contacting the volatilized oil with the house dust mite feces. McKechnie et al. volatilize the oil in numerous ways including: heating the oil to form vapors; vaporizing the oil from a heated wick dipped into a reservoir of the oil; and by utilizing an ultra-sonic jet nebuliser which contains water with the oil floated on the surface of the water. As with Miller discussed above, tea tree and other oils which are not water soluble can be difficult to work with and difficult to effectively vaporize.
Based on the foregoing, a simple, cost effective method of neutralizing the feces allergens of house dust mites is needed. The method preferably will involve simple, water soluble, compositions which are easy to work with and easily atomizable, in contrast to the oils disclosed in the prior art.